With regard to the significant properties and characteristic features of the present invention, several types of telephone exchanges or telephone stations are known to the art which fulfill the aforesaid conditions that are fundamental to the function of the present invention.
The present invention is based on the use of a telephone subscribes exchange incorporating a switchboard function to as a call transfer or "transfer function".
The call transfer function as such is-earlier known and is included in many telephone switchboards, such as subscriber exchanges. During a call in progress between a calling person, i.e. a first person, and a called person, a second person, the call transfer function enables the called, second person, to call a third person and transfer the call in progress so as to establish a call connection between the calling person, i.e. the first person, and the third person called by the second person, without the second person taking part in the call transfer.
Such a call transfer function is initiated by the called, second person, by activating a switch on the telephone keyboard (normally a button) in a manner applicable to the telephone switchboard or exchange concerned.
The second person is then disconnected completely from the call connection established by the call transfer function between the first and the third persons.
The telephone switchboard retailed by "Ericsson" of Stockholm, Sweden, under the designation "AXE-station", is an example of a telephone switchboard or exchange that is provided with such a call transfer function.
The present invention can be expected to obtain particular application as a so-called taxi-exchange, i.e. a telephone switch which is particularly adapted for taxi vehicles, where a telephonist is able to receive and to give information concerning the transportation requirements of customers, etc., where each customer is able to dial a single telephone number, preferably a readily memorized telephone number, for a particular group of taxi vehicles.
With regard to telephone switchboards which are adapted for use with taxi vehicles or other transportation means, it is known to provide each taxi with a computer and printer and to transmit printed messages to a particular taxi from a telephone switchboard with the aid of wireless or cordless data transmission means.
This system also enables each taxi to indicate to the switchboard and/or its telephone operator the area and/or the location in which the taxi concerned is found at any one particular time, this information being inserted into a queue system so that should a person require the services of a taxi and call the telephone switchboard, the telephonist is able to communicate with that taxi which has the highest priority on the list and is, at that moment in time, nearest to the address of the person concerned or has the easiest route to said address.
Telephone exchange systems which are adapted for communication with taxis by means of radiowave transmission are also known to the art.
Telephone exchange systems adapted for servicing a large number of taxis are always manned by a greater or smaller number of telephone operators.
Also belonging to the prior art is a system in which a stationary subscriber is able to dial a group number and the call is switched directly to a mobile subscriber apparatus which while being free to take an incoming call is not necessarily free to accept a fare, irrespective of the geographical position of the taxi, it being possible to connect a call directly between the stationary subscriber apparatus and the mobile subscriber apparatus selected randomly by the telephone system.
The publication SE-B-402513 discloses a system, constituting the background art for the present invention. However, the known system (page 4) is constructed so that the caller must know a code, related to the area including the address, and the used telephone number must include two digits (Ni.N2) identifying said area.
The present invention has as its goal to eliminate these two digits.